Machine for impregnating electric insulation



J. W. OLSON Oct. 29 1946.

MACHINE FOR'IMPREGNATING ELECTRIC INSULATION Filed Sept. 16, 1943 MOL TE 1V 6'4 TUE/4N T IINVENTOR. Q1 0 Ly. W 011% ATTORNEYS Patented Oct. 29, 1946 FOR IMPREGNATING ELECTRIC INSULATION John W. Olson, Hastin gs-on-Hudson, N. Y., as-

signor to Anaconda Wire and Cable Company,

New York, N. Y.,

a corporation of Delaware Application September 16, 1943, Serial No. 502,631

This invention relates to insulated electric conductors, and has for its object the provision of certain improvements in saturating or impregnating the fibrous insulation of such conductors with a bituminous or asphaltic saturant.

Certain types of electric conductors and cables are insulated with fibrous material, uch as paper, cotton'and the like, impregnated with a Water- 9 claims. (01. 91 13 proofing bituminous or asphaltic-saturant. At

normal 'room temperatures, the saturant is usually a solid or very viscous material, and it is hencethe usual practice to heat the saturant to -a temperature at which it is a mobile liquid, usually about, 350-375 F. When the fibrous insulation is immersed in this hot molten saturant, excessive moisture in the fibrous material is promptly volatilized, frequently with explosive violence. Under normal'atmospheric conditions, the fibrous insulation usually contains 4-5% of moisture, and when such fibrous insulation is immersed in the hot saturant a substantial proportion, if not all, of, this moistureis volatilized with attendant objectionable ebullition and foaming of the bath of hot saturant. The fibrousinsulation is frequently a hard, tough, dense material such askraft paper, and evenwhen substantialy dry such materialis difficultly and often incompletelyimpregnated with the saturant. In other cases the fibrous insulation isa'a comparatively soft porous paper, such as towelingstock, crumpled and twisted about the conductor and characterized by a multiplicity of minute interstitial spaces which are diflicultly filled with the saturant solely-by capillary action.

Bulk-drying of the fibrous insulation prior to impregnation has heretofore been commercially l practiced. In accordance with the customary practice, the conductor covered with the fibrous insulation is wound on reels and dried-for about 16 hours in a dry kiln at a temperature of about 200-250 F. The covered wire is usually tightly wound on the reel to a radial thickness of about one foot. The inner turns on the reel are seldom satisfactorily dried, and frequently contain upto 3% of moisture, Moreover, due to the physical discomfort in entering the drykiln, the workmen usually take out two or more reels at a time, and often appreciable moisture is 're-absorbed bythe fibrous material while the reel is exposed to the atmosphere awaiting to be .run through the saturant.

Vacuum oven drying has also been proposed for drying the fibrous insulation prior to impreg nation with the hot saturant, but this hasvproved little, if any, better than simple kilndrying. In

aforementioned improvements in the United States patent of Johnson and Olson No. 2,228,766, there is disclosed a combined and simultaneous drying and evacuating of thefibrous insulation with immediate impregnation by the saturant. In passing the dried and evacuated covered Wire immediately and directly into the hot saturant, atmospheric pressure is permitted to force the saturant to a considerable height in an upright evacuated chamber, thus, in eiiect,

sealing the end of the chamber communicating with the bath of hot saturant. Such simultaneous drying and evacuating requires careful regulation and control to satisfactorily attain the two objectives.

The present invention contemplates an improved apparatus for impregnating the fibrous insulation of electric conductors and cables with a hot saturant, particularly of the bituminous or asphaltic type. More particularly the invention aims to provide an improved apparatus for sealing the exit or rear end of a vacuum chamber in direct operative communication with a hot saturant bath beneath the surface thereof. In accordance with the invention, the electric conductor surrounded by, or covered with fibrous insulation is drawn through a die loosely surrounding it and positioned at the exit end of a vacuumcham'ber into a bath of hot saturant in direct communication with the vacuum chamber, and saturant drawn toward the die by the vacuum within the chamber is artificially chilled. The thus chilled saturant cooperates with the die and the covered conductor traveling therethrough to eiic-ctively seal the exit end of the vacuum chamber. The invention further contemplates a novel combination of apparatus .for carrying out the foregoing improvements in impregnating fibrous insulatio with a saturant.

The foregoing and other novel features of the invention will be better understood from the fol-' lowing description taken in conjunction with the accompanying drawing, in which Fig. lgis an elevation, partly in section, of a co-mbinationof apparatus embodying the invention,: and particularly adapted for practicing the impregnating fibrous insulation with a saturant, and

Fig.2 is, an enlarged sectional elevation of the endof the Vacuum chamber, in theapparatus of Fig. Loommunicating with the saturant.

The, drawing illustrates the impregnation of a layer of fibrous insulation 5 surrounding and covering an electric conductor 6, either stranded or solid, With ahot molten saturant l, The covered conductor is drawn (in th direction of the with a pusher saturant, several convolution of the covered conductor are drawn over the surface of a rotatably mounted drum 8. The drum 8 may, if desired, be

appropriately driven by any suitable source of power, or it may rotate freely and all the power required to draw the covered wire through the apparatus may be applied to the aforementioned winding-up reel. The rate of travel of the conductor and the number of convolutions wound around the drum 3 are correlated to provide a sufficiently long immersion period and satisfactorily impregnate the fibrous insulation. With a hot molten saturant of bituminous or asphaltic nature maintained at a temperature of about 350-375" F., immersion times of from 6 to 20 minutes are common. It is to be undenstood, however, that the invention is not limited to saturants of this nature, but is applicable to any kind of saturant for the fibrous insulation of electric conductors and cables. The saturant i is contained in a tank 9. A wiper I!) secured to one side of the tank removes excess saturant from the covered conductor as it is drawn from the tank. It will be understood that the drum 8 is provided device of conventional construction for properly aligning the first and last convolutions of covered conductor thereon with the respective points of supply and withdrawal.

In accordance with the embodiment of the invention illustrated in the drawing, the covered conductor is drawn through an'evacuating device immediately preceding its immersion in the bath of hot saturant. The evacuating device comprises an elongated vacuum chamber H connected by a pipe [2 to an air pump or other suitable means (not shown) for maintaining as high a vacuum as possible in the chamber, say approximating 30 inches of mercury. In practice, the vacuum chamber H may be from 3 to feet in length, or even longer if necessary. It is preferably cylindrical with a sectional diameter several times the diameter of the largest covered conductor to be passed therethrough. A removable steel die I3 is mounted at the entrance or forward end of the vacuum chamber, and is secured in position by a threaded nut I4. The traveling covered conductor fits tightly in the die l3 and effectively seals this end of the vacuum chamber.

The exit or rear end of the vacuum chamber has an inner shoulder l5 and a prolong Hi to which is coupled an extension I! extending below the surface of the bath of saturant. The diameter of the prolong and extension may be somewhat less than the diameter of the vacuum chamber, but still sufficient to freely accommodate the largest covered conductor to be passed therethrough. The extension is coupled and secured to the prolong by a threaded nut 18.

Aremovable steel die I!) abuts against the shoulder l5 and is firmly held in position by the traveling covered conductor which fits loosely in this die. A water jacket or chamber surrounds the die I9, and serves to artificially cool the die. Any other suitable means for artificially cooling the die l9 and the exit end of the vacuum chamber may be provided. An opening or manhole 2i and a cover 22 therefor are provided in the vacuum chamber near the exit end for permitting access to the chamber when changing the die l9. The evacuating device is supported by a bracket 23 secured to the side of the tank 9 and a post to completely 24 near the forward end of the device. The dies l3 and [9 may be of different sizes to accommodate different sizes of covered conductor. As previously stated, the covered conductor makes a tight fit in the die l3 and a loose fit in. the die l9.

In practicing the invention the covered conductor is drawn through the sealing die 13 into the vacuum chamber II. In its travel through the vacuum chamber, air and other gases are almost completely removed from the interstitial spaces of the fibrous insulation. The evacuated covered conductor is drawn through the exit die IQ of the vacuum chamber and immediately contacts the saturant which is drawn up the extension 11 into the prolong [6 as a result of the vacuum and the comparatively loose fit between the covered conductor and the die 19. However, the saturant will not pass beyond the die l9 into the vacuum chamber, because of the cooling effect of the water jacket 20. The artificial cooling at the exit end of the vacuum chamber chills the saturant in the adjacent part of the prolong IE to a very viscous and almost solid condition, and this chilled saturant cooperates with the die 19 and the traveling covered conductor toeffectively seal the exit end of the vacuum chamber. At the same time, the travel of the covered conductor through the die IE! keeps the die clear, and carries back into the hot saturant in the prolong or extension any accumulation of chilled saturant that might otherwise tend to clog the die. The exit end of the vacuumtube is thus sealed by the die 19, and the traveling covered conductor in conjunction with the chilled saturant surrounding the covered conductor as it enters the prolong I6.

The invention provides a simple and effective apparatus for saturating or impregnating the fibrous insulation of electric conductors and cables with hot molten saturant. Evacuating and impregnating are carried out in a substantially continuous and rapid manner. The sealing of the exit end of the vacuum chamber by the chilled saturant in cooperation with the adjacent die is simple, effective and automatic. The apparatus is of simple construction and of suitable proportions for mill operations. The dies l3 and 19 are readily changed, and no loss of time is involved in changing these dies to conform to covered conductors and cables of difierent sizes.

I claim:

1. The combination with means for holding a hot saturant bath for impregnating fibrous insulationsurrounding an electric conductor, of an elongated vacuum chamber operatively communicating with said chamber and having a removable die at each end thereof for sealing the ends of the chamber when the conductor with its covering of fibrous insulation is drawn through the chamber and the saturant in a substantially continuous manner.

2. In the combination of claim 1, a tubular extension communicating at one end with and removably attached to the vacuum chamber and extending at the other end into and beneath the surface of the saturant.

3. In the combination of claim 1, a tubular extension communicating at one end with and removably attached to the vacuum chamber and extending at the other end into and beneath the surface of the saturant, and a man-hole in the vacuum chamber approximate the end attached to said extension for facilitating access to the adjacent die,

4. In the combination of claim 1, artificial cooling means associated with the die in that end of the vacuum chamber adjacent the saturant bath,

5. The combination with means for holding a hot saturant bath for impregnating fibrous insulation surrounding an electric conductor, of an elongated vacuum chamber having one end in communication with the saturant bath beneath the surface thereof, a die at the forward end of the chamber adapted to fit tightly about the covered conductor, a die at the rear end of the chamber adapted to fit loosely about the covered conductor, and artificial cooling means associated with the die at the rear end of the chamber.

6. The combination of claim 5 in which each of the dies is removable.

7. The combination with means for holding a hot saturant bath for impregnating fibrous insulation surrounding an electric conductor, of an elongated vacuum chamber, a tubular extension communicating at one end with and removably attached to the vacuum chamber and extending at the other end into and beneath the surface of the saturant, a die at the forward end of the chamber adapted to fit tightly about the covered conductor, a die at the rear end of the chamber adapted to fit loosely about the covered conductor, and artificial cooling means approximate the juncture of said extension and vacuum chamber for-chilling saturant drawn toward the adjacent die by the vacuum within the chamber.

8. The combination with means for holding a hot saturant bath for impregnating fibrous insulation surrounding an electric conductor, of an hot saturant bath for impregnating fibrous insulation surrounding an electric conductor, of an elongated vacuum chamber, a tubular extension communicating at one end with and removably attached to the vacuum chamber and extending at the other end into and beneath the surface of the saturant, a removable die at the forward end of the chamber adapted to fit tightly about the covered conductor, a removable die at the rear end of the chamber adapted to fit loosely about the covered conductor, a manhole in the vacuum chamber approximate the end attached to said extension for facilitating access to the adjacent die, and a water jacket operatively surrounding the die at the rear end of the vacuum chamber.

JOHN W. OLSON. 

